1. Field of the Invention
The present invention relates to pavement marking devices and more specifically to semi-collapsible pavement marking devices whose respective marking part(s) move away from the force created by an object which may come into contact with the device.
2. History of the Prior Art
Conventional pavement marking devices utilized in warm climates, which are subjected to snow or ice conditions, are rigid and are secured and protrude above the pavement surface, when they are subjected to the scraping action of snow clearing equipment they are inevitably destroyed. Those conventional marking devices utilized in cold climates, which are subject to snow or ice conditions, have a base which is installed in such a manner that the upper plane of the base is, for the most part, flush with the surface of the pavement. A reflective surface is mounted upon a reciprocating stem which is anchored to, or is slidably mounted in, the base which allows the stem to protrude above the base and therefore above the pavement surface. The anchored stem type allows the stem, should it be struck, to move away from the force acting upon it. However when snow packs or ice forms around and about the device it renders it a rigid body and prevents the stem from moving away from the source of impact, ultimately leading to the destruction and failing of the device due to the overwhelming forces acting upon it. While the above shortcomings are also true for the type which incorporate a slideably mounted stem, the slideably mounted type has yet another shortcoming because the stem is designed to move only in a vertical direction, the stem can only readily react under a load that is acting directly downwards upon it, and such is not the case with regard to a snowplow blade which exerts a force upon the side of the stem and which, when traveling at normal highway speeds, intercepts and passes by the device in approximately one-thousandth of a second, during which time the device cannot respond quickly enough to prevent undue stress from developing within the device, which ultimately leads to its destruction. Another shortcoming both types of marking devices have in common is that all allow for a space to exist within the exterior of the device for the reciprocation of the stem, which in itself makes the device prone to contamination from road debris or from the natural elements and such contamination could lead to the failing of the device.
Another shortcoming of the stem type road marker becomes apparent should the stem suffer damage for it cannot be easily repaired since it is, for the most part, an integral component of the device as a whole.
The present invention is designed to eliminate these troublesome problems by offering a practical device of simple construction which is efficient and durable for marking the various lanes used for vehicular travel.
The following patents are known to Applicant and illustrate the above prior art: U.S. Pat. Nos.
1,777,585 PA0 1,888,447 PA0 2,224,937 PA0 3,502,008 PA0 2,073,968 PA0 4,049,358 PA0 2,127,700 PA0 2,157,059